Halsey 1997.
| Methods |
Study design: open‐label, randomised trial Setting: children's hospital, Buffalo, USA Assessment of immunogenicity. Venous blood samples were obtained at 2, 6 and 7 months of age and from participants at two of the study sites at 15 and 16 months of age. Polio antibody responses were evaluated at 2, 6, 7, 15 and 16 months of age. Poliovirus‐neutralising antibody titres were measured by a micrometabolic inhibition assay in Vero cells, a modification of a method previously described. Study dates: not reported |
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| Participants |
Sample size: 295 children aged 6‐10 weeks old, recruited from 1991 Dropouts/withdrawals: 22 (12 = voluntarily withdrawn by their parents, 7 = noncompliant with study visits, 2 = lost to follow‐up, 1 = due to unusually high‐pitched cry after dose 1) Age: mean = 8.7 weeks Sex: male = 49.8%, female = 50.2% Inclusion criteria: healthy infants 6 to 12 weeks of age Exclusion criteria: not reported |
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| Interventions |
Group A (n = not reported): IIIO at birth, 2, 4, 6 and 15 months; Group B (n = not reported): II(I+O)O at birth, 2, 4, 6 and 15 months; Group C (n = not reported): IIIOO at birth, 2, 4, 6 and 15 months. (Measurement at month 7 was used as III group) Each 0.5‐ml dose of IPV (IPOL™; Pasteur Merieux Connaught, Swiftwater, PA) contains 40 D antigen units of type I (Mahoney strain), 8 D antigen units of type 2 (MEFI strain) and 32 D antigen units of type 3 (Saukett strain) poliovirus grown in Vero cell cultures. Orimune® OPV (Lederle Laboratories, Pearl River, NY). |
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| Outcomes |
Timing of outcome assessment: 2, 6, 7, 15 and 16 months Follow‐up: 4.6 months |
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| Notes | ||
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Unclear risk |
Quote: "Infants were randomly assigned to one of three groups at the time of enrolment" In favour of a appropriate randomisation process Quote: "Baseline characteristics were similar by study group for the 295 children enrolled in the trial." |
| Allocation concealment (selection bias) | Unclear risk | Comment: not described |
| Blinding of participants and personnel (performance bias) All outcomes | Low risk | Comment: no blinding but performance is not likely to be influenced by lack of blinding in terms of intervention or co‐interventions |
| Blinding of outcome assessment (detection bias) All outcomes | Low risk | Quote: "All serologic testing was performed by technicians blinded to the study group" |
| Incomplete outcome data (attrition bias) All outcomes | Low risk | Comment: 12 infants were voluntarily withdrawn from the study by their parents. 7 infants were noncompliant with study visits, 2 were lost to follow‐up and 1 infant was withdrawn because of an unusual high‐pitched cry after dose 1. The distribution of withdrawals was similar by study group. Information was collected on 280 (94.9%) enrolled children at 6 months of age and 134 children at 15 and 16 months of age. |
| Selective reporting (reporting bias) | Low risk | Comment: no evidence of selecting reporting |
| Other bias | Low risk | Comment: no evidence of other bias |
| Conflict of interest | Unclear risk | Comment: grant from Pasteur Merieux Connaught, Inc |